Electrochemical characterization of Au/ZnO/PPy/RGO nanocomposite and its application for simultaneous determination of ascorbic acid, epinephrine, and uric acid

A new electrochemical sensor has been developed based on the reduced graphene oxide (RGO)/polypyrrole (PPy)/zinc oxide (ZnO)/gold (Au) nanoparticles nanocomposite modified glassy carbon electrode (GCE) for simultaneous determination of ascorbic acid (AA), epinephrine (EP), and uric acid (UA). The morphology and structure of Au/ZnO/PPy/RGO nanocomposites were characterized by field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The Au/ZnO/PPy/RGO/GCE-based sensor exhibited excellent electrocatalytic activity and high stability for determination of AA, EP, and UA. The prepared electrode separates the oxidation peak potential of AA-EP by 130 mV, and EP-UA by 150 mV, while the bare GCE cannot resolve them. Simultaneous determination of these species in their mixture solution showed a wide linear response 2–950 μM, 0.6–500 μM and 1.0–680 μM for AA, EP, and UA, respectively. The detection limits of AA, EP, and UA were also calculated as 0.16, 0.06 and 0.09 μM (S/N = 3), respectively. In addition, the proposed sensor shows good selectivity and stability along with good precision and consistency.